The invention relates to disposable flashlamp units for use with photographic cameras and particularly to such units which utilize a plurality of flashlamps. Even more particularly, the invention relates to units of the variety described wherein the flashlamps are electrically activated.
Examples of the above units currently available on the marketplace include the earlier popular "flashcube" models and the more recently introduced "flashbar" and "flip-flash" units. These units are shown and described in U.S. Pat. Nos. 3,327,105 (Kottler et al), 3,598,984 (Slomski), and 3,937,946 (Weber), respectively. The flashlamps utilized therein usually depend on activation from a power source within the camera, typically in the form of dry cell batteries or piezoelectric elements. As illustrated in the above patents, optimization of light output during lamp firing is only possible by orienting the lamp such that at least part of the longitudinal body thereof faces the subject being photographed. A single, curvilinear reflector, usually formed from a sheet of synthetic plastic material, is located behind and along side portions of each lamp to further enhance forward output therefrom.
Understandably, the aforedescribed required positioning relationships do not readily permit miniaturization of the product, particularly when said product includes several (e.g. eight or more) flashlamps. A typical "flip-flash", for example, possesses a length of about 4.75 inches, a width of about 2.0 inches, and a thickness (depth) greater than about 0.5 inches. Connecting tabs protruding from the product's ends add even further to the length dimension.
An attempt to achieve miniaturization while still providing the features desired in such flashlamp products (e.g. several lamps, relatively high output, etcetera) is shown in U.S. Pat. No. 4,098,565 (deWeijer). One problem inherent in this device, however, is the ready opportunity for sympathetic flashing between two adjacent lamps due to the required close spacing thereof. It is established in the photoflash lamp art that radiant energy emitted from a fired lamp will cause an adjacent lamp to also ignite when the spacing therebetween is less than approximately twice the lamp diameter. In no case should the distance be less than 2R(.sqroot.3-1), where R is the radius of one lamp. Another disadvantage of the flashlamp unit of U.S. Pat. No. 4,098,565 is that said unit can only be utilized with a camera or attachment which includes a relatively complex, fixed reflector. Understandably, such a requirement necessitates extensive modification to current camera lines potentially desirous of utilizing such a product. Still further, any misalignment between the camera reflector and flashlamp unit will have an adverse affect on the ultimate light output.
It is believed therefore that a flashlamp unit which readily lends itself to miniaturization while still assuring relatively high output from each of several flashlamps contained therein will constitute a significant advancement in the art.